What is gasoline made of?

Gasoline is composed of around 500 different hydrocarbon compounds that generally have between five and 12 carbon atoms each. These are mostly aromatic hydrocarbons and cyclic alkane hydrocarbons. This means that the carbon compounds in gasoline are mostly arranged in rings with single or alternating double bonds.

In addition to the ring hydrocarbon compounds, gasoline also contains between 30 and 50 percent straight chain and branched hydrocarbon compounds. Gasoline refiners obtain the particular mix for gasoline from crude oil by fractional distillation. This uses the different boiling points of different components of crude oil to isolate hydrocarbon compounds with the desired range of carbon atoms.